Marrone also turned to Schwartz’s former staff to address another need by agreeing to hire Todd Downing to coach the young crop of quarterbacks, led by last year’s rookie first-round pick, EJ Manuel.

The additions were announced Friday night, a day after defensive coordinator Mike Pettine left the team after one year to take over as the Cleveland Browns’ head coach.

“We are excited to add a talented and accomplished coordinator in Jim Schwartz to our staff,” Marrone said in a statement released by the team. “Schwartz has led aggressive and productive defensive units throughout his time in the NFL, and we feel our defense will continue to improve under his leadership.”

Schwartz was fired Dec. 30, a day after the Lions missed the playoffs with a 7-9 record. In four seasons in Detroit, the 47-year-old Schwartz was 29-51. That included a 10-6 finish in 2011 when the Lions reached the playoffs for the first time in 12 years.

Schwartz becomes the Bills’ fourth defensive coordinator in four years and has big shoes to fill in taking over a unit that emerged as the team’s strength last season.

Pettine’s departure had the potential of under-cutting much of the progress the Bills hoped would carry over into next season after a 6-10 finish that extended the NFL’s longest active playoff drought to 14 seasons.

Though the Bills were inconsistent against the run, they still finished 10th in the NFL in fewest yards allowed — Buffalo’s best ranking since finishing second in 2004. And they finished second in the NFL with a franchise-record 57 sacks.

Schwartz has 20 years of NFL coaching experience, including eight seasons as the Tennessee Titans defensive coordinator from 2001-08.

The Titans’ defense three times finished among the NFL’s top 10 in fewest yards allowed. Tennessee was particularly stingy in stopping the run, finishing sixth or better in yards rushing allowed, including a first-place ranking in 2003.

It’s unclear how many positions Schwartz will have to fill on his defensive staff because there’s a chance Pettine may lure some of his assistants to Cleveland. The Bills currently have one opening after inside linebackers coach Chuck Driesbach was fired last week.

Schwartz takes over unit that produced four Pro Bowl selections, defensive linemen Mario Williams, Kyle Williams and Marcell Dareus and safety Jairus Byrd. Byrd’s status is uncertain after he played under a one-year franchise tag last season.

The defense also includes linebacker Kiko Alonso, an NFL rookie of the year candidate.

Schwartz has a fiery personality, and an aggressive approach to defense much like Pettine, which is being counted on to ease the transition.

The knock against Schwartz in Detroit was the Lions’ inconsistencies and undisciplined style of play. In 2012, the Lions lost their last eight games after a 4-4 start. Last season, they collapsed during a stretch in which they blew fourth-quarter leads in losing six games during a seven-game stretch.

Downing’s addition filled Marrone’s desire to add a quarterbacks coach to his staff after offensive coordinator Nathaniel Hackett doubled at the position last year. Marrone had expressed an intention to ease Hackett’s burden entering his second season.

Lack of experience and injuries didn’t help the position. Manuel missed six games because of knee injuries. Undrafted journeyman Thad Lewis went 2-3 in five starts, while undrafted rookie Jeff Tuel struggled in a 23-13 loss to Kansas City.

Downing has 11 years of NFL coaching experience, and spent the past three seasons at the same position in Detroit, where he mentored Lions starter Matthew Stafford.

The 33-year-old Downing is familiar with Lewis, who spent last offseason in Detroit before the Bills acquired him in a trade in August. And he also coached Manuel at last year’s Senior Bowl.

“Todd Downing is a bright and energetic coach,” Marrone said. “He played a pivotal role in the development of Detroit’s quarterbacks during his tenure: most notably Matthew Stafford, the franchise’s all-time leading passer. Downing will be a valuable addition to our offensive coaching staff.”

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.